While I concur with your hesitation, my first reaction on hearing about the fee was "Didn't they say you couldn't fly without a realid? Why am I able to fly without one then?" The idea that they may not be able to bar you without one jives with how this is playing out. Another commenter in this post also mentioned flying without id, which I also thought wasn't possible.

If you don't have Real ID they perform an equivalent background check at the airport which they charge you $45 for.